[CMake] ExternalProject questions

[Michael Wild]

Hi all

I have a few questions concerning the new ExternalProject module  
(which, by the way is fantastic and really simplifies my code).

1. From my understanding of the ExternalProject_Add documentation,  
shouldn't INSTALL_DIR be passed on the configure-line as - 
DCMAKE_INSTALL_PREFIX:PATH=${INSTALL_DIR} when configuring a CMake- 
based project? As far as I can tell, <INSTALL_DIR> is never used in  
_ep_add_configure_command (and also no other place, although the  
ExternalProject_Add_Step does the substitution).

2. Is it possible to have the library produced by ExternalProject_Add  
depend on the target created by ExternalProject_Add? This would  
greatly simplify dependency tracking for me.

3. It would be really useful if CMake implemented a '-E patch'  
command. In the same line, it would be great if ExternalProject_Add  
had a PATCH_FILE <patch> option, which allows one to simply pass it a  
patch which applies with -p1 to the source directory.

Michael